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          <h1 class="post-title" itemprop="name headline">原型和原型链</h1>
        

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        <h1 id="原型"><a href="#原型" class="headerlink" title="原型"></a>原型</h1><blockquote>
<p>每一个javascript对象(除null外)创建的时候，就会与之关联另一个对象，这个对象就是我们所说的原型，每一个对象都会从原型中“继承”属性。</p>
</blockquote>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 父类</span></span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">People</span> </span>&#123;</span><br><span class="line">    <span class="keyword">constructor</span>(name) &#123;</span><br><span class="line">        <span class="keyword">this</span>.name = name</span><br><span class="line">    &#125;</span><br><span class="line">    eat() &#123;</span><br><span class="line">        <span class="built_in">console</span>.log(<span class="string">`<span class="subst">$&#123;<span class="keyword">this</span>.name&#125;</span> eat something`</span>)</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">// 子类</span></span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">Student</span> <span class="keyword">extends</span> <span class="title">People</span> </span>&#123;</span><br><span class="line">    <span class="keyword">constructor</span>(name, number) &#123;</span><br><span class="line">        <span class="keyword">super</span>(name)</span><br><span class="line">        <span class="keyword">this</span>.number = number</span><br><span class="line">    &#125;</span><br><span class="line">    sayHi() &#123;</span><br><span class="line">        <span class="built_in">console</span>.log(</span><br><span class="line">            <span class="string">`姓名：<span class="subst">$&#123;<span class="keyword">this</span>.name&#125;</span> 学号：<span class="subst">$&#123;<span class="keyword">this</span>.number&#125;</span>`</span></span><br><span class="line">        )</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">Teacher</span> <span class="keyword">extends</span> <span class="title">People</span> </span>&#123;</span><br><span class="line">    <span class="keyword">constructor</span>(name, major) &#123;</span><br><span class="line">        <span class="keyword">super</span>(name)</span><br><span class="line">        <span class="keyword">this</span>.major = major</span><br><span class="line">    &#125;</span><br><span class="line">    teach() &#123;</span><br><span class="line">        <span class="built_in">console</span>.log(</span><br><span class="line">            <span class="string">`<span class="subst">$&#123;<span class="keyword">this</span>.name&#125;</span> 教授 <span class="subst">$&#123;<span class="keyword">this</span>.major&#125;</span>`</span></span><br><span class="line">        )</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">let</span> xialuo = <span class="keyword">new</span> Student(<span class="string">'夏洛'</span>, <span class="number">20</span>)</span><br><span class="line"><span class="built_in">console</span>.log(xialuo.name)</span><br><span class="line"><span class="built_in">console</span>.log(xialuo.number)</span><br><span class="line">xialuo.eat()</span><br><span class="line">xialuo.sayHi()</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="keyword">let</span> wanglaoshi = <span class="keyword">new</span> Teacher(<span class="string">'王老师'</span>, <span class="string">'语文'</span>)</span><br><span class="line"><span class="built_in">console</span>.log(wanglaoshi.name)</span><br><span class="line"><span class="built_in">console</span>.log(wanglaoshi.major)</span><br><span class="line">wanglaoshi.eat()</span><br><span class="line">wanglaoshi.teach()</span><br></pre></td></tr></table></figure>
<h3 id="类型判断-instanceof"><a href="#类型判断-instanceof" class="headerlink" title="类型判断 - instanceof"></a>类型判断 - instanceof</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line">xialuo <span class="keyword">instanceof</span> Student <span class="comment">// true</span></span><br><span class="line">xialuo <span class="keyword">instanceof</span> People <span class="comment">// true</span></span><br><span class="line">xialuo <span class="keyword">instanceof</span> <span class="built_in">Object</span> <span class="comment">// true</span></span><br><span class="line"></span><br><span class="line">[] <span class="keyword">instanceof</span> <span class="built_in">Array</span> <span class="comment">// true</span></span><br><span class="line">[] <span class="keyword">instanceof</span> <span class="built_in">Object</span> <span class="comment">// true</span></span><br><span class="line"></span><br><span class="line">&#123;&#125; <span class="keyword">instanceof</span> <span class="built_in">Object</span></span><br></pre></td></tr></table></figure>
<h3 id="原型-1"><a href="#原型-1" class="headerlink" title="原型"></a>原型</h3><p><img src="https://i.loli.net/2020/09/26/MXuR5YLWwcBpdg8.png" alt></p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// class 实际上是函数，课件是语法糖</span></span><br><span class="line"><span class="keyword">typeof</span> People <span class="comment">// 'function'</span></span><br><span class="line"><span class="keyword">typeof</span> Student <span class="comment">// 'function'</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 隐式原型和显示原型</span></span><br><span class="line"><span class="built_in">console</span>.log(xialuo.__proto__)</span><br><span class="line"><span class="built_in">console</span>.log(Student.prototype)</span><br><span class="line"><span class="built_in">console</span>.log(xialuo.__proto__ === Student.prototype)</span><br></pre></td></tr></table></figure>
<h3 id="原型关系"><a href="#原型关系" class="headerlink" title="原型关系"></a>原型关系</h3><ul>
<li>每个class都有显示原型 prototype</li>
<li>每个实例都有隐式原型<strong>proto</strong></li>
<li>实例的<strong>proto</strong>指向对应class的prototype</li>
</ul>
<h3 id="基于原型的执行规则"><a href="#基于原型的执行规则" class="headerlink" title="基于原型的执行规则"></a>基于原型的执行规则</h3><ul>
<li>获取属性xialuo.name或执行方法xialuo.sayHi()时</li>
<li>先在自身属性和方法寻找</li>
<li>如果找不到则自动去<strong>proto</strong>中寻找</li>
</ul>
<h1 id="原型链"><a href="#原型链" class="headerlink" title="原型链"></a>原型链</h1><blockquote>
<p>原型链就是在访问一个对象属性的时候，如果自身没有找到的情况下会去它的原型对象中查找，如果还没有，会去它的原型对象的原型对象中查找，如此循环直到顶层的Object对象的原型对象(是个null，Object.prototype.<strong>proto</strong>===null）为止的这么个机制</p>
</blockquote>
<p><img src="https://i.loli.net/2020/09/26/UbYNtm1LyJGdQZj.png" alt></p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">xialuo.hasOwnProperty(<span class="string">'name'</span>) <span class="comment">// true</span></span><br><span class="line">xialuo.hasOwnProperty(<span class="string">'sayHi'</span>) <span class="comment">// false</span></span><br><span class="line">xialuo.hasOwnProperty(<span class="string">'hasOwnProperty'</span>) <span class="comment">// false 这个方法是从Object上面拿的</span></span><br></pre></td></tr></table></figure>
<blockquote>
<p> hasOwnProperty 判断对象是否包含特定的自身（非继承）属性</p>
</blockquote>
<p><img src="https://i.loli.net/2020/09/26/6LKAF7HZv4bnCJp.png" alt></p>
<p><strong>Tips:</strong></p>
<ul>
<li>class是ES6语法规范，由ECMA委员会发布</li>
<li>ECMA只规定语法规则，即我们代码的书写规范，不规定如何实现</li>
<li>以上实现方式都是V8引擎的实现方式，也是主流的</li>
</ul>
<h1 id="手写简易JQuery-考虑插件和扩展性"><a href="#手写简易JQuery-考虑插件和扩展性" class="headerlink" title="手写简易JQuery 考虑插件和扩展性"></a>手写简易JQuery 考虑插件和扩展性</h1><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br></pre></td><td class="code"><pre><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">Jquery</span> </span>&#123;</span><br><span class="line">    <span class="keyword">constructor</span>(selector) &#123;</span><br><span class="line">        <span class="keyword">const</span> result = <span class="built_in">document</span>.querySelectorAll(selector)</span><br><span class="line">        <span class="keyword">this</span>.length = result.length</span><br><span class="line">        <span class="keyword">for</span> (<span class="keyword">let</span> i = <span class="number">0</span>; i &lt; <span class="keyword">this</span>.length; i++) &#123;</span><br><span class="line">            <span class="keyword">this</span>[i] = result[i]</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="keyword">this</span>.length = <span class="keyword">this</span>.length</span><br><span class="line">        <span class="keyword">this</span>.selector = selector</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    get(index) &#123;</span><br><span class="line">        <span class="keyword">return</span> <span class="keyword">this</span>[index]</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    each(fn) &#123;</span><br><span class="line">        <span class="keyword">for</span> (<span class="keyword">let</span> i = <span class="number">0</span>; i &lt; <span class="keyword">this</span>.length; i++) &#123;</span><br><span class="line">            <span class="keyword">const</span> elem = <span class="keyword">this</span>[i]</span><br><span class="line">            fn(elem)</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="keyword">return</span> <span class="keyword">this</span></span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    on(type, fn) &#123;</span><br><span class="line">        <span class="keyword">return</span> <span class="keyword">this</span>.each(<span class="function"><span class="params">elem</span> =&gt;</span> &#123;</span><br><span class="line">            elem.addEventListener(type, fn, <span class="literal">false</span>)</span><br><span class="line">        &#125;)</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">// const $p = new Jquery('p')</span></span><br><span class="line"><span class="comment">// p.get(0)</span></span><br><span class="line"><span class="comment">// p.each(elem =&gt; console.log(elem))</span></span><br><span class="line"><span class="comment">// p.on('click', (e) =&gt; console.log(e))</span></span><br><span class="line"><span class="comment">// p.dialog().show()</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 插件</span></span><br><span class="line">Jquery.prototype.dialog = <span class="function"><span class="keyword">function</span>(<span class="params">info</span>) </span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="string">'调用dialog方法'</span>)</span><br><span class="line">    <span class="comment">// 实现jQ链式调用的原理， 返回了当前的this就可以继续访问自己的原型</span></span><br><span class="line">    <span class="keyword">return</span> <span class="keyword">this</span></span><br><span class="line">&#125;</span><br><span class="line">Jquery.prototype.show = <span class="function"><span class="keyword">function</span>(<span class="params">info</span>) </span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="string">'调用show方法'</span>)</span><br><span class="line">    <span class="keyword">return</span> <span class="keyword">this</span></span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">// 造轮子</span></span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">myJQuery</span> <span class="keyword">extends</span> <span class="title">Jquery</span> </span>&#123;</span><br><span class="line">    <span class="keyword">constructor</span>(selector) &#123;</span><br><span class="line">        <span class="keyword">super</span>(selector)</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="comment">// 扩展自己的方法</span></span><br><span class="line">    addClass() &#123;</span><br><span class="line"></span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    style(data) &#123;</span><br><span class="line"></span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

      
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              resultContent.innerHTML = '<div id="no-result"><i class="fa fa-search fa-5x" /></div>'
            } else if (resultItems.length === 0) {
              resultContent.innerHTML = '<div id="no-result"><i class="fa fa-frown-o fa-5x" /></div>'
            } else {
              resultItems.sort(function (resultLeft, resultRight) {
                if (resultLeft.searchTextCount !== resultRight.searchTextCount) {
                  return resultRight.searchTextCount - resultLeft.searchTextCount;
                } else if (resultLeft.hitCount !== resultRight.hitCount) {
                  return resultRight.hitCount - resultLeft.hitCount;
                } else {
                  return resultRight.id - resultLeft.id;
                }
              });
              var searchResultList = '<ul class=\"search-result-list\">';
              resultItems.forEach(function (result) {
                searchResultList += result.item;
              })
              searchResultList += "</ul>";
              resultContent.innerHTML = searchResultList;
            }
          }

          if ('auto' === 'auto') {
            input.addEventListener('input', inputEventFunction);
          } else {
            $('.search-icon').click(inputEventFunction);
            input.addEventListener('keypress', function (event) {
              if (event.keyCode === 13) {
                inputEventFunction();
              }
            });
          }

          // remove loading animation
          $(".local-search-pop-overlay").remove();
          $('body').css('overflow', '');

          proceedsearch();
        }
      });
    }

    // handle and trigger popup window;
    $('.popup-trigger').click(function(e) {
      e.stopPropagation();
      if (isfetched === false) {
        searchFunc(path, 'local-search-input', 'local-search-result');
      } else {
        proceedsearch();
      };
    });

    $('.popup-btn-close').click(onPopupClose);
    $('.popup').click(function(e){
      e.stopPropagation();
    });
    $(document).on('keyup', function (event) {
      var shouldDismissSearchPopup = event.which === 27 &&
        $('.search-popup').is(':visible');
      if (shouldDismissSearchPopup) {
        onPopupClose();
      }
    });
  </script>





  

  

  

  
  

  

  

  

</body>
</html>
